JP2000225673A - Biaxially stretched double-layered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially stretched double-layered film having high speed automatic packaging aptitude, markedly reduced in the antistaining properties to a packaging machine and excellent in transparency, low temp. heat sealability, scratch resistance and slip-off resistance. SOLUTION: A biaxially stretched double-layered film is obtained by laminating a layer comprising a compsn. containing 100 pts.wt. of a propylene random copolymer, 0.05-1.0 pts.wt. of fine particles of a crosslinked polymer comprising a copolymer of a monomer containing a specific functional group and 0.01-5 pts.wt. of an acid modified polyolefinic resin on at least the single surface of a substrate layer based on a crystalline propylene polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretched multilayer film, and more particularly to transparency and low-temperature heat sealability, scratch resistance, which have high suitability for high-speed automatic packaging and significantly reduce contamination to packaging machines. The present invention relates to a biaxially stretched multilayer film having good properties.

[0002]

2. Description of the Related Art A biaxially stretched multilayer film, for example, a biaxially stretched polypropylene film having a heat-sealing layer laminated thereon, has various characteristics such as transparency and rigidity, and is used for overlapping foods, cigarettes, cassette tapes and the like. It is widely used as a packaging film, but with the recent development of high-speed automatic packaging machines, the required quality of the film for automatic packaging suitability has been more advanced than ever. That is, as the most important required performance in the film for overlap packaging,
Low-temperature heat sealability is mentioned, as a method for imparting this low-temperature heat sealability, a resin having a low-temperature heat sealability when producing a biaxially oriented polypropylene film, for example, propylene / ethylene random copolymer or propylene / A method for laminating an ethylene / butene-1 copolymer or the like has been developed, and further, by adding a second component such as polybutene-1 to this layer, the low-temperature heat sealability has been greatly improved. As a measure for improving the suitability of a film packaging machine in response to the recent increase in speed of an automatic packaging machine, a method of adding inorganic fine particles such as silica or calcium carbonate to the above resin (Japanese Patent Publication No. Hei 4-30347). Alternatively, a method of adding organic fine particles such as a spherical silicone resin powder (Japanese Patent Laid-Open No. 62-233248) has been proposed, and a great improvement effect can be obtained with respect to speeding up of an automatic packaging machine. ing.

However, when high-speed automatic packaging is performed for a long period of time using a biaxially oriented multilayer film in which a low-temperature heat-sealable resin containing inorganic or organic fine particles is added to the surface of a biaxially oriented polypropylene film, It has been found that there is a disadvantage that the added fine particles fall off and the packaging machine is contaminated. Therefore, the present inventors have proposed a method of adding an acid-modified resin as a third component in addition to the fine particles (JP-A-6-297657) in order to prevent falling off. At present, it has not yet obtained a sufficient effect to further increase the speed.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transparent and low-temperature heat-sealable, scratch-resistant and anti-blocking agent having high-speed automatic packaging suitability and significantly reduced contamination to packaging machines. An object of the present invention is to provide a biaxially stretched multilayer film having excellent resistance to falling off.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have used a specific amount of crosslinked polymer fine particles obtained by copolymerizing a monomer containing a carboxyl group as an antiblocking agent, and It has been found that a biaxially stretched multilayer film that solves the above problems can be obtained by using a specific amount of the acid-modified polyolefin-based resin of the present invention, and has reached the present invention. That is, the present invention provides the following (A), (B) and (C) on at least one surface of a crystalline propylene-based polymer or a base material layer containing these as a main component.
A biaxially stretched multilayer film characterized by laminating layers composed of a composition containing components. (A) 100 parts by weight of a propylene-based random copolymer (B): 1 to 50% by weight of a radical polymerizable monomer unit having a carboxyl group in a polymer chain;
A copolymer containing 49 to 98% by weight of a radical polymerizable monomer unit other than the above: a crosslinked polymer fine particle having a volume average particle diameter of 0.3 to 10 μm, which is a copolymer containing 1 to 20% by weight of a crosslinked monomer unit; 0.0 parts by weight (C) The acid value defined by JIS K0070 is 1.0 to 1.0 parts by weight.
0.01 to 5 parts by weight of 100 mg KOH / g acid-modified polyolefin resin

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. [I] Biaxially stretched multilayer film The biaxially stretched multilayer film of the present invention comprises the following components (A) and (B) on at least one surface of a crystalline propylene-based polymer or a base layer containing the same as a main component. ) And a composition comprising component (C). (1) Base material layer (a) Crystalline propylene polymer (essential component) The crystalline propylene polymer used for the base layer of the biaxially stretched multilayer film of the present invention is a propylene homopolymer or Propylene and other α-olefins (ethylene, butene, hexene, 4-methylpentene, octene, etc.), unsaturated carboxylic acids or derivatives thereof (acrylic acid, maleic anhydride, etc.), aromatic vinyl monomers (Styrene, etc.) and random, block or graft copolymers. The isotactic index (II) of such a crystalline propylene polymer is 40%.
Above, among them, 60% or more, especially 80% or more is preferable. Therefore, it is most preferable to use a propylene homopolymer. It is preferable to use those having an I of 90% or more, especially 95% or more, particularly 98% or more, from the viewpoints of the stiffness of the film, the paper dropping property of the film feeding portion, and the suitability for high-speed automatic packaging. The melt flow rate (MFR) is 0.5 to 10 g / 10
Min, especially 1 to 5 g / 10 min. These crystalline propylene-based polymers can be used alone or as a mixture of plural kinds of polymers, or a resin containing a crystalline propylene-based polymer as a main component may be used.

(B) Other compounding agents (optional components) The base material layer of the biaxially stretched multilayer film of the present invention contains the above-mentioned crystalline propylene-based polymer as a main component and other compounding materials having the characteristics described below. It may be blended in an amount within a range not to decrease, for example, in a range of 30% by weight or less. Examples of such blending materials include ethylene polymer, butene polymer, petroleum resin, terpene resin, and styrene resin. And other thermoplastic polymers such as hydrocarbon polymers (including hydrogenated products thereof). Further, to the crystalline propylene polymer of the base material layer, of course, additives such as stabilizers such as antioxidants and weathering agents, processing aids, coloring agents, antistatic agents, lubricants, antiblocking agents, etc. May be included. Among these additives, those containing an antistatic agent are particularly preferable. Preferred examples of the antistatic agent include fatty acid esters of glycerin, alkylamines, ethylene oxide adducts of alkylamines, and fatty acid esters thereof. In the case of a film to which good antistatic performance has not been imparted, static electricity may accumulate during running of the film, resulting in poor paper dropping properties.

(2) Surface Layer The surface layer of the biaxially stretched multilayer film of the present invention is laminated on one or both sides of a substrate layer formed from the above-mentioned crystalline propylene polymer. Is formed from a resin composition for a surface layer containing the following components (A), (B) and (C).

(A) Surface layer resin composition (i) Constituent components (essential components) (A) Component Propylene random copolymer The propylene random copolymer used as the component (A) is propylene Examples thereof include an ethylene random copolymer and a propylene / ethylene / butene-1 random copolymer. Specifically, the propylene / ethylene random copolymer resin has an ethylene content of 2 to 10% by weight, preferably 3 to 8% by weight, particularly preferably 4 to 6% by weight. When the ethylene content in the propylene / ethylene random copolymer resin is less than the above range, the heat sealability tends to be reduced.
If the ethylene content exceeds the above range, the film tends to be sticky and the scratch resistance tends to decrease. The propylene / ethylene / butene-1 random copolymer resin has an ethylene content of 0.3 to 6% by weight, preferably 0.5 to 5% by weight, particularly preferably 1 to 5% by weight.
4% by weight and a butene-1 content of 2 to 30
% By weight, preferably 3 to 25% by weight, particularly preferably 5% by weight.
~ 20% by weight. The propylene / ethylene /
If the ethylene content or butene-1 content in the butene-1 random copolymer resin is less than the above range, the heat sealability tends to decrease, and if the ethylene content or butene-1 content exceeds the above range, The film becomes sticky and the scratch resistance tends to decrease. In addition, the melt flow rate (MFR) of these propylene-based random copolymers is generally 0.4 to 100 g / 10 minutes,
Preferably 0.5 to 50 g / 10 min, more preferably 1 to 20 g / 10 min, particularly preferably 2 to 10 g / 10 min.
Minutes.

Component (B) Crosslinked Polymer Fine Particle The crosslinked polymer fine particle used in the present invention is a polymer containing one or more radically polymerizable monomers having a carboxyl group, and a monomer unit copolymerizable with the monomer and a crosslinkable polymer. Fine particles containing a copolymer having a monomer unit. The structure of the crosslinked polymer particles is
It may have a multilayer structure of two or more layers. In this case, it is sufficient that the copolymer in the outermost layer has the above composition. The shape of the crosslinked polymer fine particles is not particularly limited, but is preferably substantially spherical.

The radically polymerizable monomer containing a carboxyl group only needs to have a carboxyl group in the molecule. For example, acrylic acid, methacrylic acid, α-chloroacrylic acid, α-bromoacrylic acid, crotonic acid, silica Examples thereof include cinnamic acid, fumaric acid, maleic acid and anhydrides thereof. The ratio of the radically polymerizable monomer having a carboxyl group to all monomer units is 1 to 50% by weight, preferably 1 to 20% by weight. If it is less than 1% by weight, the crosslinked polymer fine particles fall off, and if it exceeds 50% by weight, the crosslinked polymer fine particles aggregate.

The monomers copolymerizable with the above-mentioned carboxyl group-containing radical polymerizable monomer include, for example, methyl acrylate, ethyl acrylate, n-acrylate
-Butyl, isobutyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacryl (Meth) acrylic monomers such as n-octyl acid, dodecyl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, methyl 5-hexenoate, styrene, o-methylstyrene, m-methylstyrene and p-methylstyrene , Α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m
-Chlorostyrene, styrene-based monomers such as p-chlorostyrene, ethylene, propylene, butylene, vinyl chloride, vinyl acetate, acrylonitrile, acrylamide,
N-vinylpyrrolidone and the like can be mentioned. It is also possible to use these monomers in combination. The ratio of the monomer copolymerizable with the radically polymerizable monomer having a carboxyl group to all monomer units is 49 to 98% by weight, preferably 51 to 96%.
% By weight. If it is less than 49% by weight or more than 98% by weight, the suitability for high-speed automatic packaging is deteriorated.

Examples of the crosslinkable monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, decaethylene glycol diacrylate, pentadecaethylene glycol diacrylate, 1,3-butylene diacrylate, and allyl acrylate. Pentaerythritol tetraacrylate, diethylene glycol phthalate diacrylate, pentacontaector ethylene glycol dimethacrylate, pentacontaector ethylene glycol diacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethacrylyl Acid pentaerythritol, 1,1,1-trishydroxymethylethane diacrylate, triac 1,1,1-trishydroxymethylethane acrylate, 1,1,1-trishydroxymethylpropane triacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene dimethacrylate Glycol, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, allyl methacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, diethylene glycol dimethacrylate phthalate, etc. (Meth) acrylic monomer, divinylbenzene, divinylnaphthalene,
Examples thereof include aromatic divinyl compounds such as these derivatives, crosslinking agents such as N, N-divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfonic acid, and polybutadienes, polyisoprenes, and unsaturated polyesters. The ratio of the crosslinkable monomer to all monomer units is 1 to 20% by weight, preferably 3 to 18% by weight. If it is less than 1% by weight, the suitability for high-speed automatic packaging cannot be obtained, and if it exceeds 20% by weight, scratch resistance deteriorates.

Examples of the method of copolymerizing the above-mentioned carboxyl-containing radical polymer monomer with a copolymerizable monomer and a crosslinkable monomer include emulsion polymerization, dispersion polymerization, suspension polymerization and soap-free polymerization. , A seed polymerization method, a swelling polymerization method, a microsuspension polymerization method, and a graft polymerization method.

The average particle size of the crosslinked polymer fine particles used in the present invention is 0.3 to 10 μm, preferably 0.7 to 3 μm in volume average particle size. When the average particle diameter is less than 0.3 μm, sufficient automatic packaging suitability cannot be imparted when formed into a film, and when the average particle diameter exceeds 10 μm, transparency, falling resistance, and scratch resistance deteriorate. .

Component (C) Acid-Modified Polyolefin Resin The acid-modified polyolefin resin used in the present invention is a polyolefin resin in which at least a part of its terminals is acid-modified, and has an acid value of 1. specified in JIS K0070. 0 to
100 mg KOH / g, preferably 5 to 60 mg KOH
/ G. When the acid value is less than 1.0 mgKOH / g, the transparency and the falling resistance deteriorate. On the other hand, 100mgK
If it exceeds OH / g, operability deteriorates. Examples of the polyolefin include homopolymers or copolymers of propylene, ethylene, butene-1, hexene-1,4-methylpentene-1 and the like, and mixtures of these polymers,
Especially, it is preferable to use low molecular weight polypropylene.

The low molecular weight acid-modified polypropylene has a number average molecular weight of 800 to 20,000, preferably 1,000.
0 to 18,000 acid-modified polypropylene (hereinafter sometimes simply referred to as “acid-modified low molecular weight PP”). The acid-modified low molecular weight PP is obtained by chemically adding an unsaturated carboxylic acid and / or an anhydride thereof described below to a low molecular weight polypropylene having a terminal double bond,
Alternatively, it is synthesized by reducing the molecular weight of ordinary acid-modified propylene, and at least a part thereof is acid-modified at its terminal. The acid-modified polypropylene obtained by the acid modification generally has a softening point of 130 to
It indicates a temperature of 170 ° C, preferably 140 to 160 ° C.

Preferred low molecular weight polypropylene having a terminal double bond is 1 to 1 per 1,000 carbons.
It has 0, preferably 2 to 7 terminal double bonds, and has a number average molecular weight of 800 to 20,000, preferably 1,000 to
18,000. If the terminal double bond is less than the above range, desired acid modification may not be performed. If the terminal double bond exceeds the above range, the heat resistance of the acid-modified low molecular weight PP tends to decrease. . Further, when the number average molecular weight exceeds the above range, the prevention of the fine particles from falling tends to decrease.

The acid modification is carried out by a melt grafting method or a solution grafting method. In the melt grafting method, the reaction temperature is usually 100 to 270 ° C., preferably 130 to 240 ° C., usually 0.5 to 30 hours. It is preferably carried out under the conditions of a reaction time of 1 to 20 hours. In the solution grafting method, after completely dissolved in xylene, a peroxide is used in combination, and the reaction with an unsaturated carboxylic acid and / or an anhydride thereof is usually performed at 120 to 180 ° C, preferably 140 to 180 ° C.
The reaction is carried out at a reaction temperature of 160 ° C., usually for a reaction time of 1 to 20 hours, preferably 3 to 15 hours. Then, a precipitate is obtained using a large amount of acetone or the like. The product obtained by the acid modification contains generally 0.01 to 20%, preferably 0.05 to 15%, particularly preferably 0.1 to 10% by weight of unsaturated carboxylic acid and / or anhydride thereof.
Is desirably contained at a ratio of

The unsaturated carboxylic acid as a modifying agent includes:
Examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and nadic acid. Examples of the unsaturated carboxylic anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride, allyl succinic anhydride, and nadic anhydride. Among these, it is preferable to use maleic anhydride. Such an acid-modified polyolefin may be a directly modified one diluted with an unmodified one, and may be appropriately selected from commercially available ones and used.
For example, Umex series (manufactured by Sanyo Chemical Industries, Ltd.)
And commercially available maleic anhydride-modified polypropylene.

(Ii) Other Constituents (Additional Components) In addition to these essential constituents, the surface layer of the biaxially stretched multilayer film of the present invention may be further improved. Alternatively, additional components other than the above essential components can be added for other purposes. As the additional component, for example, 5 to 45 parts by weight of a crystalline butene-1 polymer or a propylene / butene-1 copolymer is added to 100 parts by weight of the above component (A), so that the low-temperature heat treatment is performed. The sealing performance can be further improved. Examples of such a crystalline butene-1 polymer include a homopolymer of butene-1 and a copolymer of butene-1 with another α-olefin such as ethylene or propylene. Use of a copolymer having an MFR equal to or larger than the MFR of the component (A) at the same temperature in the range of 180 to 300 ° C. can improve transparency. It is preferable because it can be performed. In order to improve the suitability for high-speed packaging, it is preferable to add an organic lubricant such as various silicone oils and silicone gums. Particularly preferred lubricants have a polymerization degree n of 3,500 to
8,000 polydiorganosiloxane gums, or
Addition of 0.1 to 1 part by weight of a silicone oil having a viscosity of 100 to 100,000 centistokes is exemplified.

(Iii) Mixing ratio The mixing ratio of each component of the surface layer composition comprising the above components (A), (B) and (C) is determined based on a propylene random copolymer. Can be (B) Component Crosslinked Polymer Fine Particles The blending amount of the crosslinked polymer fine particles blended as the component (B) in the propylene-based random copolymer is 0.05 to 100 parts by weight of the propylene-based random copolymer.
1.0 parts by weight, preferably 0.1 to 0.5 parts by weight. If the amount is less than the above range, packaging suitability cannot be imparted. On the other hand, if the amount exceeds the above range, the falling of the crosslinked polymer fine particles cannot be prevented even if the component (C) is mixed, and also the transparency of the film deteriorates.

Component (C) Acid-Modified Polyolefin Resin The amount of the acid-modified polyolefin resin blended as the component (C) in the propylene random copolymer is 100 parts by weight of the propylene random copolymer. 0.
It is 0.01 to 5 parts by weight, preferably 0.03 to 4.5 parts by weight. If the amount is less than the above range, the crosslinked polymer fine particles cannot be prevented from falling off. On the other hand, if the compounding amount exceeds the above range, not only is the heat sealing property deteriorated, but also the cost is increased, such being undesirable. Also,
By adding the component (C) to the spherical crosslinked polymer fine particles having a large effect of improving the suitability for packaging among the components (B), the effect of preventing the crosslinked polymer fine particles from falling can be further exhibited.

(B) Production of Surface Layer Composition The surface layer composition constituting the surface layer of the biaxially stretched multilayer film of the present invention comprises the above components (A), (B) and (C). It is preferable that the mixture is mixed by a mixer such as a Henschel mixer, a V blender or a ribbon blender, and then kneaded by a kneader such as an extruder. Also, component (B)
A better effect can be obtained by preparing a masterbatch in which the component (C) and the component (C) are blended in a larger amount than a predetermined amount and diluting the masterbatch at the time of molding. However, it is desirable to avoid using a method in which the component (B) and the component (C) are separately blended and diluted at the time of molding, since the improvement effect is reduced.

(3) Thickness The thickness of the biaxially stretched multilayer film thus obtained is determined according to its use.
m, preferably in the range of 10 to 60 μm. The ratio of the surface layer to the base material layer is usually 1 to 20%, preferably 1.5 to 10%. The thickness of the surface layer of the biaxially stretched multilayer film is generally 0.2 to 3 μm, preferably 0.3 to 2.0 μm. If the thickness of the surface layer exceeds the above range, transparency may be poor. If the thickness is less than the above range, uniform heat sealing strength may not be provided.

[II] Production of Biaxially Stretched Multilayer Film (1) Lamination The biaxially stretched multilayer film of the present invention comprises a crystalline propylene polymer or at least one surface of a base material layer containing the same as a main component. It is manufactured by laminating and stretching a surface layer formed from a composition for a surface layer containing the above components (A), (B) and (C). As a method of laminating the surface layer composition comprising the component (A), the component (B) and the component (C) on the crystalline propylene polymer of the base material layer,
For example, on one or both sides of the crystalline propylene polymer of the base material layer, the composition for the surface layer is formed into a sheet by melt co-extrusion, and a method of biaxially stretching these is easy for this composition. It is preferable because it can be laminated uniformly and thinly. However, a method in which the composition for a surface layer is melt-extruded and coated on an unstretched or uniaxially stretched base layer sheet and then biaxially stretched or uniaxially stretched in a direction perpendicular to the stretching direction of the base layer can also be adopted. .

(2) Stretching Of the above-described biaxial stretching, longitudinal stretching can be performed by utilizing a difference in roll peripheral speed. That is, 90 ° C.
The film is stretched 3 to 8 times, preferably 4 to 6 times at 140 ° C., preferably 105 to 135 ° C., and subsequently stretched 3 to 12 times, preferably 6 to 11 times in the transverse direction in a tenter oven. In order to prevent heat shrinkage at the time of heat sealing, it is desirable to heat set at a temperature of 120 to 170 ° C. subsequent to the transverse stretching.

(3) Other Treatments Corona treatment or the like can be performed for the purpose of promoting printability and bleeding of the antistatic agent.

[III] Applications The biaxially stretched multilayer film of the present invention has high suitability for high-speed automatic packaging, has no pollution to packaging machines, and has transparency, low-temperature heat sealability, and scratch resistance. Good for high speed automatic packaging, food, tobacco,
It can be widely used as a film for overlapping packaging such as cassette tape.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not particularly limited by the following Examples. In addition, the measured value of each item in the detailed description of the present invention and the examples was measured by the following method. (1) MFR: 23 according to ASTM-D-1238
The measurement was performed at 0 ° C. using a load of 2.16 kg. (2) Haze (unit%): Measured according to ASTM-D-1003. (3) Packaging suitability: 40 using a packaging machine made by Tokyo Automatic Machinery
The cigarettes were packed at a speed of 0 pieces / min, and the following evaluation was performed. (I) Heat sealability: After the completion of the packaging, the degree of adhesion of the tobacco to the bottom seal was evaluated. (Ii) Contamination of packaging machine: The film was placed on a packaging machine to a length of 2,000 m, and the degree of the amount of powder adhering to the packaging machine was visually evaluated according to the following criteria (3 ranks). 1: There is no generation of powder at all. 2: Powder generation is slightly observed. 3: Generation of powder is very large. (4) Scratch resistance: Observing the tobacco after packaging is completed,
The degree was visually evaluated according to the following criteria (3 ranks). 1: No scratches occurred. 2: Generation of scratches is observed. 3: Many scratches are observed.

Example 1 As a base material layer, MFR was 2.5 g / 10 min. I is 9
A mixture consisting of 95 parts by weight of 9% crystalline polypropylene homopolymer powder, 5 parts by weight of a hydrogenated terpene resin, and 0.9 parts by weight of a fatty acid ester of polyoxyethylene alkylamine was used. On the other hand, in the surface layer, 85 parts by weight of a propylene / ethylene / butene-1 random copolymer resin having an ethylene content of 2% by weight, a butene-1 content of 12% by weight, and an MFR of 5.5 g / 10 min as the component (A). And 15 parts by weight of a butene-1 / propylene random copolymer resin, and methacrylic acid / methyl methacrylate / trimethylolpropane trimethacrylate in a weight ratio of 10/80/10 as a component (B). Then, 0.3 parts by weight of a spherical crosslinked polymer fine particle having a volume average particle diameter of 1.8 μm obtained by an emulsion polymerization method, and a polypropylene modified with maleic anhydride as a component (C) (Sanyo Chemical Co., Ltd.) Industrial Co., Ltd. Umex 1001 (acid value: 26 mg
KOH / g)), and a resin composition (hereinafter abbreviated as α-layer resin) containing 4 parts by weight and 0.5 part by weight of a silicone oil having a viscosity of 10,000 centistokes was used.
As the surface layer on the other side, the propylene / ethylene / butene-1 random copolymer resin 100
A resin composition (hereinafter referred to as β) in which 0.3 parts by weight of the same component (B) and 4 parts by weight of component (C) are mixed with
Abbreviated as layer resin. )It was used.

The crystalline polypropylene mixture of the base layer and the α-layer resin and the β-layer resin were each 115 mm in diameter and 2 mm in diameter.
Using a three-layer die from an extruder of 0 mm diameter and 30 mm diameter, α layer resin / base layer / β layer resin: 0.05 mm / 1 m
It was extruded and formed into a three-layer laminated sheet having a thickness of m / 0.05 mm. This laminated sheet is stretched 5 times in the longitudinal direction at a temperature of 115 ° C. using a difference in roll peripheral speed, and then stretched in a tenter oven at a temperature of 168 ° C. to obtain a biaxially stretched multilayer film. Was manufactured. The thickness configuration of this film is 0.9 μm / 20 μm
/1.1 μm. After the corona discharge treatment was performed on the surface side of the β-layer resin of the obtained biaxially stretched multilayer film, cigarette packaging was performed so that the corona discharge treatment surface was inside.
Table 1 shows the results.

Example 2 A propylene / ethylene random copolymer powder having an MFR of 5.0 g / 10 min and 85 parts by weight of propylene / methacrylic acid / methyl methacrylate / trimethylolpropane triacrylate in a weight ratio of 5/87/8. And 10 parts by weight of a spherical crosslinked polymer fine particle having a volume average particle size of 2.2 μm obtained by an emulsion polymerization method, and UMEX 1001 manufactured by Sanyo Chemical Industries, Ltd. as an acid-modified polyolefin resin.
(Acid value: 26 mg KOH / g) 100 parts by weight of a resin composition consisting of 5 parts by weight, 0.1 part by weight of calcium stearate, 0.2 part by weight of BHT (2,6-di-tert-butylhydroxytoluene), and Ciba-Geigy Made I
After mixing 0.05 parts by weight of rganox1010 with a Henschel mixer, a master batch pellet was granulated by a 45 mm extruder. Next, a propylene / ethylene random copolymer resin having an ethylene content of 5% by weight and an MFR of 6.0 g / 10 min as the component (A) of the surface layer (α resin layer) was formed on the same base material layer used in Example 1. Except that 97.5 parts by weight and 2.5 parts by weight of the above master batch were mixed (equivalent to 0.25 part by weight of component (B) and 0.125 part by weight of component (C)), all were the same as in Example 1. To produce a biaxially stretched multilayer film, and packaging was performed. Table 1 shows the results.

Comparative Example 1 As the crosslinkable polymer fine particles used in Example 1, volume average particles obtained by changing the monomer ratio to methyl methacrylate / trimethylolpropane trimethacrylate (weight ratio): 75/25. A biaxially stretched multilayer film was produced in the same manner as in Example 1 except that fine particles of 0 μm were used, and cigarette packaging was performed. Table 1 shows the results.

[0035]

[Table 1]

[0036]

The biaxially stretched multilayer film of the present invention has a transparency by laminating a surface layer containing a specific amount of crosslinked polymer fine particles having a specific structure and a specific amount of an acid-modified polyolefin. It has good low-temperature heat-sealing properties and scratch resistance, and is suitable for high-speed automatic packaging. Even if long-term high-speed automatic packaging is performed, the added fine particles do not fall off and do not contaminate the packaging machine. It is a film that is extremely useful industrially as a layer film.

Continued on the front page (72) Inventor Gen Kanai 1 Toho-cho, Yokkaichi-shi, Mie Japan F-term in Material Development Center, Polychem Co., Ltd. AK66C AK80B AK80C AL03B AL03C AL05B AL05C AL06B AL06C BA02 BA03 BA06 BA10B BA10C BA15 DE01B DE01C EH20 EJ05B EJ05C EJ38 EJ55 GB15 JA11A JK14 JL06 JL12 JN01 YY00B YY00C 4J002 BB08X BB14X BB141 BB151 BB17X BB20Y BB21Y BC04X BC08X BC09X BC11X BD05X BF02X BG01X BG04X BG05X BG06X BG10X BG13X BH02X BJ00X GF00 GG02

Claims (2)

[Claims] 1. A layer comprising a composition containing the following components (A), (B) and (C) is laminated on at least one surface of a crystalline propylene-based polymer or a base material layer containing these as a main component. A biaxially stretched multilayer film characterized by the following. (A) 100 parts by weight of a propylene-based random copolymer (B): 1 to 50% by weight of a radical polymerizable monomer unit having a carboxyl group in a polymer chain;
A copolymer containing 49 to 98% by weight of a radical polymerizable monomer unit other than the above: a crosslinked polymer fine particle having a volume average particle diameter of 0.3 to 10 μm, which is a copolymer containing 1 to 20% by weight of a crosslinked monomer unit; 0.0 parts by weight (C) The acid value defined by JIS K0070 is 1.0 to 1.0 parts by weight.
0.01 to 5 parts by weight of 100 mg KOH / g acid-modified polyolefin resin 2. The biaxially stretched multilayer film according to claim 1, wherein the propylene random copolymer is a propylene / ethylene random copolymer or a propylene / ethylene / butene-1 random copolymer.